Direct Regeneration of Spent Graphite Anode of Lithium-ion Battery

Abstract

A method for restoring electrochemical activity and cycling stability to spent graphite anode material for a lithium-ion battery includes exposing powdered graphite anode material to boric acid to form borated material, then sintering the borated material. The processing removes dead lithium from the bulk structure and applies boron doping to surfaces of the graphite material.

1 . A method for removing bulk defects from spent graphite particles from a Li-ion battery anode, comprising:
 treating the spent graphite particles in a boric acid solution to form borated graphite particles;   drying the borated graphite particles; and   fast annealing the borated graphite particles.   
     
     
         2 . The method of  claim 1 , further comprising, prior to the step of treating, washing the spent graphite particles in a solvent and drying to form a powder. 
     
     
         3 . The method of  claim 1 , wherein the step of fast annealing comprises sintering the borated graphite particles for approximately an hour at a temperature in a range of 750° C. to 1050° C. 
     
     
         4 . A method for restoring electrochemical activity and cycling stability to spent graphite anode material for use in a lithium-ion battery comprising:
 exposing powdered graphite anode material to boric acid to form borated material; and   sintering the borated material, wherein dead lithium in a bulk structure of the graphite anode material is extracted and boron doping is applied to surfaces of the graphite material.   
     
     
         5 . The method of  claim 4 , further comprising, prior to the step of exposing, washing the spent graphite particles in a solvent and drying to form a powder. 
     
     
         6 . The method of  claim 4 , wherein the step of sintering comprises annealing the borated material for at least one hour at a temperature in a range of 750° C. to 1050° C. 
     
     
         7 . A method for regeneration of spent anode material of a lithium-ion battery comprising:
 harvesting graphite particles from the spent anode material;   washing the harvested graphite particles in a solvent solution;   precipitating graphite powder from the solution;   rinsing the graphite powder in water;   drying the graphite powder;   dispersing the graphite powder in a boric acid solution;   exposing the borated graphite powder to a drying temperature until dry; and   sintering the dried borated graphite powder at a sintering temperature for a sintering period.   
     
     
         8 . The method of  claim 7 , wherein washing the graphite particles in the solvent solution further comprises heating the solution at a temperature of 70-90° C. until dried. 
     
     
         9 . The method of  claim 7 , wherein the sintering temperature is within a range of 750° C. to 1050° C. 
     
     
         10 . The method of  claim 7 , wherein the sintering period is at least one hour. 
     
     
         11 . A method for removing bulk residual lithium and reopening channels for lithium transport from graphite anode material of a spent Li-ion battery comprising:
 exposing powdered graphite anode material to boric acid to form borated material; and   sintering the borated material, wherein boron doping is applied to surfaces of the graphite material.   
     
     
         12 . The method of  claim 11 , wherein the step of sintering comprises annealing the borated material for at least one hour at a temperature in a range of 750° C. to 1050° C.